Conventionally, blast treatment is known as a surface treating technique in which hard particles injected by compressed air are hit on a surface of a workpiece, such as a machined part or a painted part. According to the blast treatment, rust or dirt on a surface of a workpiece can be removed. Therefore, the blast treatment is used mainly for a surface treatment, such as paint peeling or shot peening, besides a substrate treatment before a paint or the like.
The blast treatment is performed by injecting blast media with compressed air from a nozzle for blast treatment toward a workpiece. Therefore, to prevent scattering of injected blast media is a problem in the blast treatment. Thus, a blast treatment device having a duct line for recovering blast media near a nozzle for injecting the blast media and having a structure in which the nozzle and the duct line for recovering the blast media are covered by a casing has been proposed so as to prevent scattering of the blast media (for example, refer to Japanese Patent Application Publication No. H08-252769, Japanese Patent Application Publication No, 2000-190226 and Japanese Patent Application Publication No, 2004-25351).
Furthermore, a technique to move a nozzle by a multijoint manipulator has been devised to clean a large workpiece, such as a panel for ship, by a sandblasting method (for example, refer to Japanese Patent Application Publication No. S59-14596). In this technique, a nozzle and a casing which covers the nozzle are configured to be self-propelled with wheels. Furthermore, a counter weight for balancing an actuator is used together as a driving source for raising the nozzle in the vertical direction.
However, the conventional blast treatment device has a problem that it is difficult to perform blast treatment of a workpiece having an irregular surface or a large area. For example, in case of a workpiece having an irregular surface, to place a casing for preventing scattering of blast media causes interference with the workpiece. Meanwhile, when a casing for preventing scattering is distanced from a workpiece or removed, scattering of blast media cannot be prevented.
Furthermore, scattering of blast media causes a problem that dust of the blast media mixes in a driving part, such as a linkage. Therefore, in case of performing blast treatment of a large workpiece which requires to move a nozzle for injecting blast media, a countermeasure has been taken so as to move the nozzle by a multijoint manipulator whose joint portions have been covered with a dust-proof cover.
However, when a multijoint manipulator is used, a moving range of a nozzle is limited depending on lengths of links of the manipulator. Therefore, when a size of a workpiece is extremely large, it is necessary to prepare a manipulator having very long links according to the size of the workpiece.
In particular, a length of a panel which is one of aircraft part is a meter order, and many panels have fixed protruding objects, such as stringers. Therefore, it is difficult to use the conventional blast treatment device for a panel of an aircraft. As a result, manual work such that a worker polishes a workpiece with a sandpaper as a substrate treatment before painting a panel for an aircraft is currently performed.
Thus, an object of the present invention is to provide a blast treatment device and a blast treatment method which can flexibly adapt to a size or a form of a workpiece and stably perform blast treatment.